Trunking communication systems are known to comprise a plurality of communication units, a limited number of communication resources that are transceived via a predetermined number of repeaters, or base stations, and a communication resource allocator that allocates a limited number of communication resources among the plurality of communication units. The communication resources may comprise a TDM bus, a carrier frequency, a pair of carrier frequencies, or any RF transmission means. Of the communication resources, one is selected as the control channel to transceive operational data between the communication resource allocator and the communication units. The communication units, which may be portable radios and/or mobile radios, are arranged into talk groups by commonality of use. For example, a talk group may comprise communications that are operated by a police department while another talk group comprises communication units operated by a fire department.
In a typically trunking communication system, the communication units transmit service request to the communication resource allocator. The service request may comprise requesting allocation of a communication resource, a change in the communication units parameters, etc. The communication allocator receives these service requests and responds to them typically in a first in first out fashion. As each service request is received, it is either processed or placed in a service request waiting queue within the communication resource allocator. When the trunking communication system is very busy, the communication resource allocator may be processing service requests at a maximum rate and yet the service request queue becomes full. Under these circumstances, service requests that are transmitted after the service request queue is full are ignored. Therefore, a need exists for a method that will allow the communication resource allocator to substantially respond to all service requests.